Circuit/System Description

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Idle Mode

At engine start, the engine control module (ECM) commands fuel pressure regulator 2 to control fuel pressure at idle. The engine will remain in this mode if the fuel temperature is below 15°C (59°F) or until fuel pressure regulator 2 adapts (which occurs at higher engine loads) or until fuel temperature reaches 60°C (140°F). The adaptation is a learned factor that adjusts fuel pressure regulator 2 current to compensate for manufacturing tolerances and component aging. Once the adaptation is complete, the vehicle will use fuel pressure regulator 1 for rail pressure control at idle. The fuel pressure regulator 2 adaptation will attempt to run again at the next drive cycle.

Post Drive Mode

During post-drive mode, the fuel pressure regulator 2 relieves any remaining fuel pressure from the rails. After a 30 second bleed-down and the ignition is off, the fuel rail pressure sensor should read atmospheric pressure and return the proper signal voltage to the ECM. When this DTC sets in post drive mode the engine will be in Reduced Power Mode on the next key cycle.